Difunctional monomers, such as 4-amino phthalic anhydride, have been polymerized with heat to form polyimides. See U.S. Pat. No. 3,450,678. Also see page 1140 of an article by Bogart and Renshaw titled "4-Amino-0-Phthalic Acid And Some of Its Derivatives" which appeared in the Journal of the American Chemical Society, Vol. 30, pages 1135 to 1144 (1908), and German Offen. Pat. Nos. 1,812,357 and 1,913,280.
Electropolymerization by condensation (e.g., loss of halogen or carbon dioxide) has been carried out with several different monomers. See pages 390 to 392 of the article by N. Yamazaki titled "Electrolytically Initiated Polymerization" which appeared on pages 377 to 400 of Advanced Polymer Science, Vol. 6 (1969). However, only a very few condensation polymers have been successfully electropolymerized since a condensation polymerization is difficult to effect electrochemically. As the Yamazaki article states on page 390 in reference to electrochemical condensation polymerization, "electrochemical reaction is not favorable for such a step-by-step reaction, since a growing polymer chain end must be affected at the electrode at each step of the reaction. Hence, only a few peculiar attempts have been found successful."